Effect analysis on hydraulic pulping coupled with anaerobic digestion of food wastes

Considering the characteristics of the high water content of food wastes, the hydraulic pulping pretreatment technology was comprehensively evaluated from the aspects of hydraulic simulation, characteristics of pulp, key equipment operation indicators and project operation effect. The CFD (computational fluid dynamics) hydraulic simulation results showed that during the pulping process, the fluid particles spirally converged to the rotor blades to form three internal swirling eddies, which produced obvious velocity and pressure differences in the fluid interior. Under the hydraulic action, the pulping of food wastes could be performed quickly. The analysis of pulp and impurity characteristics showed that the pulping product was of fine particles, with low organic matter loss and high impurity removal, which could be highly integrated with different back-end resource utilization technologies (anaerobic digestion, aerobic fermentation, etc.). Taking the resource utilization project of food waste as an example, which adopted hydraulic pulping and anaerobic fermentation technologies, the relevant operation data showed that after the pretreatment of food wastes by hydraulic pulping, the loss rate of organic matter was about 8.5%, the separation rate of non-biodegradable impurities was about 94%, and the extraction rate of crude oil was about 91%. Moreover, the average oil production rate per ton of food waste was 3.76%, and the gas production rate per ton of food waste was 85.57 m³. The treatment method had a higher resource utilization rate compared to mechanical pre-treatment, which could greatly improve the economic benefits of the project.